This invention relates to an electrical melting apparatus, especially for slag-shielded electrical melting, having at least one vertical column, a mold, and at least two electrode holding arms which can be swung alternately into the melting position above the mold, and each of which is disposed on an electrode feeder which can travel vertically on guides independently of one another.
Columns for slag-shielded electrical melting are known, which are in the form of profiles, round or polygonal hollow bodies, or latticed girder poles. Electrode holding arms and/or mold supporting arms are disposed on these columns. If a horizontal swinging of the electrode holding arms for positioning of the electrodes above the melting stations or molds is necessary, either the columns are rotated together with the electrode holding arms as a whole (DE-AS 2,111,-047), or bearings about which the electrode holding arms can be pivoted are provided on the electrode feeders (DE-AS 2,134,223). Forms of construction are also known in which a plurality of vertical guiding columns are disposed coaxially with the main column and can be pivoted around the main column together with the electrode holding arms and electrode feeders (DE-PS 2,050,418).
All of the known types of construction have the disadvantage that each electrode holding arm must have its separate column provided with vertical guides. So that the electrode feeder of the electrode holding arm will not be too expensive, the main columns must be of correspondingly scanty dimensions. As a result, deformations of the main column or of the guiding column occur in the vertical movement, and also upon the horizontal rotation of the electrode holding arm, resulting in displacements of the electrode from the melting point or mold, as the case may be. Such displacements result in an off-centering of the electrode in the mold, and thus in an irregular melting and undesirable lateral current leakages as a result of the reduction of the distance between the electrode and the wall of the mold.
In the known forms of construction, slip molds and slip mold carriers are driven along the lower portion of the column on the same guides as those provided for an electrode feeder (DE-AS 2,134,223). For this it is essential that the column be appropriately stable so as to prevent any vibration due to the movement of the electrode holding arm from being transmitted to the slip mold and hence to the melt. Consideration must at the same time be given to the fact that the crystallization process by which the melt becomes the solid ingot or strand must take place in a uniform and undisturbed manner so that a uniform grain structure will develop. On account of this requirement the columns must be very sturdily constructed, and this in turn results in an increase in the size of the electrode feeder, or else separate columns must be provided for the slip mold. If in the last-named case a slip mold is provided to which consumable electrodes are fed alternately by two electrode holding arms, a total of three columns is required, along with the corresponding guides. Since the arms for carrying the electrodes and the slip mold cooperate with one another in the melting process, a precise alignment of the vertical guides of the electrode feeder and of the mold carriage is necessary with a view to the absolute parallelism of all three columns. For this purpose, it is common to provide connecting structures at the top between the columns, and in some cases the connecting structure is additionally anchored to the building for the purpose of improving the stability of the entire installation. On the one hand, these are very involved measures, and on the other hand they entail the danger that vibration of the building due to overhead cranes and the like may be transmitted to the melting installation, thereby adversely affecting the melting process. Furthermore, the planning and installation of such structures is expensive, and the alignment of the guides with one another has to be performed on the site.